Method of converting animal waste inot a multi-phase fuel

ABSTRACT

A method of converting agricultural waste to a fuel comprising adding about 5% to about 90% agricultural waste to about 10% to about 95% reaction solution of water and alcohol. The reaction solution ranges from about 100% alcohol to about 100% water. The reactants are subjected to a heat of about 230° C. to about 370° C. under a pressure of about atmospheric to about 3000 psig for three minutes or more. Another embodiment of the method of converting agricultural waste to a fuel further adds about 0.5% to about 15% of an oxidizing agent to the reactants. A further embodiment of the method of converting agricultural waste to a fuel adds about 10% to about 50% by weight of diesel fuel to the reactants.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. Provisional Patent ApplicationNumbered 60/879,478 filed on Jan. 9, 2007.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISC APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

Energy needs and the desire to protect the environment have resulted inefforts provide alternative sources of fuel. To date, in addition to theconventional fossil fuel sources and the use of nuclear energy, numerousalternative energy sources have been utilized such as the wind, ormechanical or thermal use of large bodies of water. Also, with respectto environmental considerations, low sulfur coal and methods forcleaning the exhaust from the use of fossil fuels have been utilized.

The U.S. Department of Energy is faced with the immense task ofbalancing the energy demand of our society with the environmentalconsequences of generating that energy. The primary focus has been onthe efficiency of conversion of fuel to a useful form of energy. Energycan simply be defined as the ability to do work. The energy value of afuel normally is measured by temperature change as a result ofoxidation. Fundamentally fuels are valued by their ability to supplyheat. In the traditional sense, combustion processes produce heat fromthe fuel. As fuel is oxidized, heat is released. The heat is convertedthrough some mechanical means to a more useful form of energy forapplication. As the efficiency of the conversion increases, the negativeimpact on the environment decreases.

Previously, it has been shown that after reaction with water near thecritical condition large portions of animal wastes, namely manures, canbecome soluble-. In initial experiments a blend comprised of afifty/fifty by weight blend of agricultural waste and water was heatedto nearly 360° C. and held at that temperature for about one hour. Inthose conditions the water reacted with parts of the agricultural wasteto produce moieties that had soluble behavior when blended with dieselfuel. Although only initially partially soluble, about 35%, blending theinsoluble portion with a surfactant, lecithin, and emulsifying with thediesel fuel mixture enriched the initial blend so that the final blendhad compositions containing nearly 50% converted agricultural. Theseblends were used to operate or fuel a diesel engine. However, thereaction conditions were somewhat extreme. The vapor pressure of waterat 360° C. is 2705 psia (pounds per square inch absolute). This reactionwould require thick wall reactors and special training. Further one ofthe difficulties with this procedure was that the blend of 50% water 50%agricultural waste has a thick consistency and is difficult to handle.Finally, the heat transfer from the reactor walls to the mixture is nothomogenous and some charring was seen at the reactor wall surface.

In another experimental version the agricultural waste conversion waterwas again blended with agricultural waste to create a blend at the50%/50% level. But to this blend diesel fuel was added to make the blendmore fluid. Mixing in some diesel fuel decreased the viscosity of theblend and facilitated the reaction. The diesel fuel was also aneffective solvent for the product. The procedure also facilitated adeashing of the agricultural waste material whereas the ash wasprevalent in the previous method. Additionally, the remaining ash couldbe recovered by simple filtration or centrifugation. However, thepercentage of the mixture that was soluble agricultural waste was fairlylow because a significant quantity of diesel fuel was required to makethe blend more fluid.

BRIEF SUMMARY OF THE INVENTION

The present invention provides for a method of converting agriculturalwaste to fuels under lessened conditions than previously possible. Oneaspect of the invention is the pretreatment of agricultural waste withan oxidizing agent. The oxidizing agent such as hydrogen peroxide couldbe added before the alcohol water mixture, or the addition of airbubbling through the blend could be the oxidizing agent. Additionally,even without the pretreatment a blend of agricultural waste and animproved water/alcohol reaction solution could produce a fuel under lessextreme conditions than previously possible. The reaction solution couldhave very high concentrations of alcohol. At these different reactionsolution concentrations, the addition of diesel fuel may also not beneeded as it was at earlier when no alcohol was added to the reactantmixture as in previous experiments.

DETAILED DESCRIPTION OF THE INVENTION

In this application agricultural waste can be lagoon waste, animal wasteand manures, cellulose waste such as wood waste corn stover and humansewage sludge, organic wastes such as paper pulp mill black liquorwaste, and animal mortalities that are a hazard in the animal productionindustry.

Previous procedures for the conversion of agricultural waste to fuelsutilized extreme conditions. The procedures required an aqueous solutionto be heated to 360° C. The vapor pressure of water at this temperatureis 2705 psia (pounds per square inch absolute) and additionally a gas isproduced. Any gaseous products added to the total pressure inside aclosed reactor and the end pressure of the procedure. Usually at atemperature around 360° C. the pressure is about 3000 psig. Theprocedure would be much more attractive if that pressure could bedropped significantly and the solubility of the agricultural waste couldbe enhanced and the fuel product could be completely deashed Sinceagricultural waste is mostly carbon with oxygen linkages it was feltthat partially oxidized waste would produce more acids and these acidscould be reacted with alcohols.

In organic chemistry one of the common oxidizing agents is hydrogenperoxide. Samples of agricultural waste were placed in variousconcentrations of hydrogen peroxide from 5% to 50%. Reaction solutionscomprised of aqueous solutions of alcohol were blended with theprereacted agricultural waste. Pretreated agricultural waste isagricultural waste that is combined with 5% hydrogen peroxide. It issuspected that the hydrogen peroxide reacted with the lignin typematerial. 500 grams of an alcohol/water reaction solution comprised of40% n-propyl alcohol and 60% water was blended with 500 grams ofpretreated agricultural waste and put into a closed reactor. 700milliliters of diesel fuel was added to the blend. The reaction wascompleted when the mixture reached a final temperature of 360° C. butthe pressure only reached 1400 psig. This is about 1000 psig less thatthe regular pressure of previous reactions. Further there was anenhanced solubility of agricultural waste in both the aqueous and dieselfuel fractions. Any commercial oxidizing agent such as hydrogen peroxidecould potentially be used or the blend could be heated to about 200° C.and air bubbled through the blend for industrial use. The use of bubbledair would exploit the oxygen in air as the oxidizer. In this applicationair could be intake air from the atmosphere, air from a tank, or blendsof oxygen one skilled in the art would use for optimal oxygen intakeinto the reaction. The cost for such a procedure would be minimal.

In addition to adding oxidizing agents, the water and alcoholconcentrations in the reaction solution were adjusted. A second reactionwithout any water composed of a blend of a 50% methyl alcohol reactionsolution and 50% dried hog lagoon waste was prepared, but notpretreated. Five hundred grams of each component were mixed. The blenddid not get pasty as when the dried lagoon waste was blended with wateralone as a reaction solution. 350 grams of diesel fuel was added,however, it is suspected that diesel fuel may not be needed. The mixture500 grams alcohol reaction solution/500 grams died lagoon waste/350grams diesel fuel was heated to 360° C. The pressure in various runs ofthis experiment never got above 2000 psig. It is believed that thereaction conditions could be even milder with oxidation pretreatment ofthe agricultural waste. The system was permitted to return to roomtemperature. When the reactor was opened a small amount of gas evolved.The contents actually bubbled. The non-gas phase contents of the reactorwere removed. There were two phases: a solid and a single-phase liquid.The phases can be separated by any means known to one skilled in the artto readily separate a solid and a liquid such as centrifugation. Thesolid was separated by centrifugation using about 2000 g's. The solidreadily separated. The liquid remained a single phase. This is verysignificant because methyl alcohol has no appreciable solubility indiesel fuel. The diesel fuel did not float on top of the alcoholsolution as expected. Even after centrifugation separation did notoccur. The solution could be a colloidal suspension like milk but itcould not be separated even at 2000 g's. Upon standing for one and ahalf months traces of some tar like material did separate out but it wasa minimal amount. The liquid was analyzed for fuel properties. Theliquid had a BTU value of 19,110 BTU/lb. Diesel fuel is about 18,500BTU/lb. Gasoline can be about 18,000 BTU/lb.

The reaction could be run under the following conditions; a temperaturerange of about 230° C. to about 370° C.; a solid agricultural waste toreaction solution concentration ranging from about 5% agriculturalwaste/95% reaction solution to about 90% agricultural waste/10% reactionsolution. In addition, the reaction solution concentration could have arange of about 100% alcohol/0% water to about 0% alcohol/100% water withany water/alcohol concentrations available for use with the alcoholbeing a methyl, ethyl, or any other alcohol with the C_(n)H_(2n+1)OHformula. One example is a solution of about 15% alcohol to about 85%water with the alcohol being a methyl alcohol. The pressure could rangefrom about atmospheric to about 3000 psig in a closed reactor with areaction time between about three minutes and about one hour.Pretreatment of the agricultural waste with an oxidizing agent couldmake the conditions of reaction even milder. The pretreatment could bein a range of about 0.5% oxidizer/95.5% agricultural waste to about 15%oxidizer/85% agricultural waste with the oxidizer being any that onewith normal skill in the art would use such as hydrogen peroxide. Inaddition, diesel fuel can be added to the mixture in a range of Thatrange is probably about 10% to about 50% mixture weight, but is notessential needed. The mixture may be blended to homogeny beforereaction, but could also be added unblended into a stirring reactor.

Example Reaction:

The experiment was a non-pretreated agricultural waste blend in a 38.5%agricultural waste/38.5% reaction solution/23% diesel fuel by weightwith the reaction solution consisting of 100% alcohol. The reactionsolution was 100% methyl alcohol. The charge to the reactor consisted of500 grams of dried hog agricultural waste consisting of manure lagoonwaste mixed with 500 grams of 100% pure methyl alcohol reactionsolution. This was mixed and added to 300 grams of diesel fuel. Thediesel fuel was in the reactor before the agricultural waste alcoholblend was prepared. The diesel fuel is added to decrease the viscosityof the blend. With the aqueous blends, the agricultural waste solutionblend has the consistency of paste. To insure more complete uniformheating, diesel fuel was added to change the paste to a fluid that couldbe easily stirred. With the 100% methyl alcohol reaction solution theblend is very fluid and the diesel fuel was probably not needed. Themixture was heated to 360° C. at a rate of 3° C. per minute in a closedreactor although it is believed that a much faster heating rate wouldaccomplish the same result. The pressure at this temperature was 450psig. If there is surplus of alcohol the pressure would equal thepressure of methanol at that temperature which is greater than 1000psia. The resultant pressure implies that there is no excess alcohol;therefore all of it must have reacted. This may not be case every timebecause if excess alcohol is used then the pressure would equal thepressure of the alcohol at this temperature.

The reactor was cooled to room temperature. There was a pressure of 60psia in the cooled vessel. This means that during the reaction betweenthe alcohol and agricultural waste some gas formed. The composition ofthat gas is not known at this time. In earlier alcohol plus watersolution reactions about 200 psia of gas was formed and that was about97% carbon dioxide. When the depressurized contents of the reactor wereremoved there were two phases: a solid and a liquid. Methyl alcohol isnot very soluble in diesel fuel so any unreacted alcohol would be aseparate liquid phase that is denser than diesel fuel. In this case thematerial is completely miscible. Centrifugation did not cause two liquidphases to form so the alcohol reaction solution reacted with theagricultural waste and formed a material that mixes with the dieselfuel. The mixture may not be a true solution but a colloid like the fatin water that is called milk.

After centrifugation the solid was weighted and a crude mass balance wasdone. Initially there were 300 grams of diesel fuel, 500 grams of methylalcohol reaction solution and 500 grams of agricultural waste. In theproduct 300 grams of diesel fuel, 400 grams of agricultural waste, and480 grams of alcohol. The 100 grams was the ash material removed assolids. Therefore the hypothesized product is about 25% diesel fuel and75% product of the alcohol reaction solution/agricultural wastereaction. However, diesel fuel may not be needed at all. The heat ofcombustion of the product as measured is 19,100 BTU/lb. This iscomparable to high quality diesel fuel and is a little higher thangasoline. It is further believed that the pretreatment of theagricultural waste with an oxidizing agent would make reactionconditions even milder.

The initial experiments have shown that the diesel fuel may not benecessary. Second the reaction conditions are much milder than whenaqueous solutions are used. The critical pressure of methyl alcohol islower than that of water. The critical temperature of methanol is 240°C. and its critical pressure is 1146 psia water has a criticaltemperature of 374° C. and its critical pressure is 3200 psia. Thismeans that the cost of equipment for the process will be less and thesystem will be much less dangerous. It should be also noted thatalthough methanol was used other alcohols should also work. Further inthe example, an agricultural waste material from a lagoon was used.However, other biowaste materials such as other animal waste, manuresand human sewage sludge. Cellulose waste such as wood waste and cornstover should also work.

These terms and specifications, including the examples, serve todescribe the invention by example and not to limit the invention. It isexpected that others will perceive differences, which, while differingfrom the forgoing, do not depart from the scope of the invention hereindescribed and claimed. In particular, any of the function elementsdescribed herein may be replaced by any other known element having anequivalent function.

1. A method of converting agricultural waste to a fuel comprising addingabout 5% to about 90% agricultural waste to about 10% to about 95%reaction solution of water and alcohol wherein said reaction solutionranges from about 100% alcohol to about 100% water and subjecting thereactants to a heat of about 230° C. to about 370° C. under a pressureof about atmospheric to about 3000 psig for three minutes or more. 2.The method of converting agricultural waste to a fuel of claim 1 whereinsaid alcohol has the formula of C_(n)H_(2n+1)OH.
 3. The method ofconverting agricultural waste to a fuel of claim 1 further comprisingblending said reactants either before administering heat or pressure orduring the administration of heat or pressure.
 4. The method ofconverting agricultural waste to a fuel of claim 1 further comprisingthe separation of phases after said reaction.
 5. The method ofconverting agricultural waste to a fuel of claim 4 wherein saidseparation is centrifugation.
 6. The method of converting agriculturalwaste to a fuel of claim 1 wherein about 0.5% to about 15% of anoxidizing agent is added to said reactants.
 7. The method of convertingagricultural waste to a fuel of claim 6 wherein said oxidizing agent ishydrogen peroxide.
 8. The method of converting agricultural waste to afuel of claim 6 wherein said oxidizing agent is air added to saidreactants.
 9. The method of converting agricultural waste to a fuel ofclaim 6 further comprising the addition of about 10% to about 50% byweight of diesel fuel to said reactants.
 10. A method of convertingagricultural waste to a fuel comprising adding about 5% to about 90%agricultural waste, about 10% to about 95% reaction solution of alcoholand water wherein said reaction solution is about 100% alcohol to about100% water, and about 0.5% to about 15 of an oxidizing agent andsubjecting the reactants to a heat of about 230° C. to about 370° C.under a pressure of about atmospheric to about 3000 psig for threeminutes or more.
 11. The method of converting agricultural waste to afuel of claim 10 wherein said alcohol has the formula ofC_(n)H_(2n+1)OH.
 12. The method of converting agricultural waste to afuel of claim 10 further comprising blending said reactants eitherbefore administering heat or pressure or during the administering ofheat or pressure.
 13. The method of converting agricultural waste to afuel of claim 10 further comprising the separation of phases after saidreaction.
 14. The method of converting agricultural waste to a fuel ofclaim 10 further comprising the addition of about 10% to about 50% byweight of diesel fuel to said reactants.
 15. The method of convertingagricultural waste to a fuel of claim 10 wherein said oxidizing agent ishydrogen peroxide.
 16. The method of converting agricultural waste to afuel of claim 10 wherein said oxidizing agent is air added to saidreactants.
 17. A method of converting agricultural waste to a fuelcomprising adding about 5% to about 90% agricultural waste, about 10% toabout 95% reaction solution of water and alcohol wherein said reactionsolution is about 100% alcohol to about 100% water, about 0.5% by weightto about 10% by weight of an oxidizing agent, and about 0% to about 50%of diesel fuel and subjecting the reactants to a heat of about 230° C.to about 370° C. under a pressure of about atmospheric to about 3000psig for three minutes or more.
 18. The method of convertingagricultural waste to a fuel of claim 17 wherein said alcohol has theformula of C_(n)H_(2n+1)OH.
 19. The method of converting agriculturalwaste to a fuel of claim 17 further comprising blending said reactantseither before administering heat or pressure or during the administeringof heat or pressure.
 20. The method of converting agricultural waste toa fuel of claim 17 further comprising the separation of phases aftersaid reaction.